UNIX System Administration A Beginner’s Guide PHẦN 1 doc

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UNIX System
Administration:
A Beginner’s Guide
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UNIX System
Administration:
A Beginner’s Guide
Steve Maxwell
McGraw-Hill/Osborne
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DOI: 10.1036/0072228334
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About the Author
Steve Maxwell has been actively involved with UNIX and computer networking
for the last 20 years. He has worked for a number of companies, institutions,
and organizations in a variety of capacities that have included network design,
software development, and training. Recently, Steve decided that it was time
to join another start-up company, and he now works at FineGround Networks,
Inc., where he is responsible for ensuring that the company delivers quality
software products. Steve welcomes your feedback on any aspect of this book—
please send comments, questions, and suggestions to
About the Technical Reviewers
John Tiso is a senior consultant for NIS, a Boston-based integrator of Sun
Microsystems and Cisco Systems. He has a B.S. degree from Adelphi University
and is certified in UNIX from HP, Sun, and IBM. John is also a Cisco CCIE
(CCIE #5162), MCSE, and MCNE. He has published papers in several leading

technical journals, such as Element K and SysAdmin, and has served as a technical
editor for a variety of books. John can be reached at
Jim Minatel is a freelance writer and editor with more than 13 years of publishing
experience in mathematics, statistics, and computing. He has authored and
co-authored several books about the Internet and World Wide Web in the early
Netscape era, and most recently served as Editor in Chief for two magazines for
networking professionals and IT managers. He holds undergraduate degrees in
mathematics and physics, and an M.S. in mathematics.
Contents
ACKNOWLEDGMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
1 Introduction to UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1. Uncover the History of the UNIX System . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Explore the Elements of a Computer System . . . . . . . . . . . . . . . . . . . . . . 3
3. Show the UNIX Timeline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
AT&T Invents UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
BSD Is Born . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
The System V Releases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
AT&T/Sun Deal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
The Internet Worm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
OSF/1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Mach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Linux Is Introduced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Red Hat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Versions of UNIX Today . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Why UNIX Is Popular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Modular UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
The Kernel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4. Discover the Roles of the UNIX System Administrator . . . . . . . . . . . . . . 18
Support the Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

vii
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viii UNIX System Administration: A Beginner’s Guide
Handle Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Manage System Upgrades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Actively Monitor System Security . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Maintain System Accounts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Advance Your Knowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Teacher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Politician . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Parent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Police Officer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Friend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2 Basic UNIX Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
1. Explore the UNIX Shell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2. Investigate Basic UNIX Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
cat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
hostname . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
find . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
ls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
ps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
uname . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Project 2-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3 Using System Administration Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
1. Managing Solaris Using Admintool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Add a New User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
UNIX Account Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Modifying a User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Deleting a User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Adding a New Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Modifying a Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Deleting a Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
2. Manage Linux Accounts with Userconf . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Add a New User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Modifying a User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Delete an Existing User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Adding a New Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
3. Manage HP-UX Using SAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Add a New User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Modifying a User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Delete an Existing User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Contents ix
Adding a New Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Deleting an Existing Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
4. Set Up Better Account Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Expiring a Password Using Admintool . . . . . . . . . . . . . . . . . . . . . . . 106
Expiring a Password Using Userconf . . . . . . . . . . . . . . . . . . . . . . . . 106
Expiring a Password Using SAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Regular Password Changes Using Admintool . . . . . . . . . . . . . . . . . . 109
Regular Password Changes Using Userconf . . . . . . . . . . . . . . . . . . . 110
Turning Off an Account Using Admintool . . . . . . . . . . . . . . . . . . . . 111
Turning Off an Account Using Userconf . . . . . . . . . . . . . . . . . . . . . . 113
Automatic Account Expiration Using Userconf . . . . . . . . . . . . . . . . 114
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
4 Software Package Management Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

1. Discover Solaris Package Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
pkginfo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
pkgadd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
pkgrm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
2. Discover HP-UX Package Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
swlist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
swinstall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Project 4-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
swremove . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Project 4-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
3. Discover Linux Package Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Project 4-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
5 Maintaining UNIX Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
1. Discover the /etc/passwd File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
2. Discover the /etc/group File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
3. Discover the /etc/shadow File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
4. Explore UNIX Account Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
passwd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
pwck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
grpck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
useradd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
userdel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
usermod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
groupadd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
groupdel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
groupmod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
logins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
vipw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
x UNIX System Administration: A Beginner’s Guide

Project 5-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
6 File Systems, Disks, and Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
1. Explore a UNIX File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
2. Uncover a Disk Partition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
3. Determine a Mounted File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Creating a New File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Using the Solaris Format Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Using the Linux fdisk Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
4. Create a New File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Checking the New File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Mounting UNIX File Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Unmounting a UNIX File System . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Project 6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
7 System Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
1. Define a Security Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
2. Maintain System Patches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
3. Uncover System Hardening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Elimination of Unnecessary Services . . . . . . . . . . . . . . . . . . . . . . . . . 201
Configuration System Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
3. Investigate Security Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
The NMAP Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Project 7-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
The Secure Shell Facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
ssh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
scp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
ssh-keygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
ssh-agent/ssh-add . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
The Sudo Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

Project 7-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
8 Backup and Restore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
1. Define Backup Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
User Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Density and Form Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Network Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Remote Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Backup Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
2. Explore Backup Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
dump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
TEAMFLY

Team-Fly
®

Contents xi
dd . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
restore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
tar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Project 8-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
9 System Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247
1. Determine the Boot Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
2. Explore the Shutdown Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Halting the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Rebooting the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
Normal System Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Determining When the System Was Halted . . . . . . . . . . . . . . . . . . . 256
3. Uncover UNIX Operating Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
The Default Run Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
List the Current Run Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
Single-User Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Boot to Single-User Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Project 9-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
10 The TCP/IP Suite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
1. Uncover the General Seven-Layer OSI Network Model . . . . . . . . . . . . . . 270

Application Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Presentation Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Session Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Transport Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Network Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Data Link Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
Physical Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
2. Discover the TCP/IP Protocol Architecture . . . . . . . . . . . . . . . . . . . . . . . 272
Process Layer Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
End-User Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
Additional Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274
System Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
Additional Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Host-to-Host Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
Internet Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
Internet Control Message Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 299
3. Discover the Address Resolution Protocol . . . . . . . . . . . . . . . . . . . . . . . . 304
Packet Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306
ARP Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
Data Link Address Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
xii UNIX System Administration: A Beginner’s Guide
11 Basic Network Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
1. Explore the Network Address Table on a UNIX System Using arp . . . . . . . . 316
Displaying the ARP Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Deleting an ARP Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Adding an ARP Cache Entry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
2. Control Network Interfaces Using Ifconfig . . . . . . . . . . . . . . . . . . . . . . . . 324
Listing Available Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Controlling Interface State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328

Modifying Interface Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
Special Configurations Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 331
Logical Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
3. Monitor Network Operations using Netstat . . . . . . . . . . . . . . . . . . . . . . . 334
Displaying Active Network Sessions . . . . . . . . . . . . . . . . . . . . . . . . . 335
Displaying Interface Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
Display Routing Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342
Display Multicast Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
Display Protocol Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
4. Verify Network Connectivity Using Ping . . . . . . . . . . . . . . . . . . . . . . . . . 346
Determine System Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
Show Basic Network Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . 350
Additional Command Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
5. Gather Network Information with Lanscan . . . . . . . . . . . . . . . . . . . . . . . 356
Project 11-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
12 Advanced Network Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
1. Monitor Network Traffic with the tcpdump Tool . . . . . . . . . . . . . . . . . . 362
Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364
Display Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368
Using Packet Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
Address Primitives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
Protocol Primitives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374
Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375
Miscellaneous Primitives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Qualifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378
Tcpdump Command Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379
2. Execute the traceroute Command to Show Network Connectivity . . . . . 382
Reading Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384
Changing Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387

Display Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389
3. Verify Basic Operations Using the landiag Command . . . . . . . . . . . . . . . 390
Project 12-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
Contents xiii
13 Overview of SNMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395
1. Discover SNMP Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
SNMP Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
2. Uncover MIBs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
Object Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 401
Sample MIB Object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404
SNMP Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406
Accessing Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410
Standard and Private MIBs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 410
SNMP Communities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
3. Explore SNMP Versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 412
SNMP Protocol Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 416
SNMP Response Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422
Transmission of an SNMP Message . . . . . . . . . . . . . . . . . . . . . . . . . . 423
Connectionless Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424
4. Investigate SNMP Master and Subagent . . . . . . . . . . . . . . . . . . . . . . . . . . 424
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 427
14 Using the Domain Name System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431
1. Discover How the Domain Name System Works . . . . . . . . . . . . . . . . . . . 432
2. Explore Both DNS Server and Client Components . . . . . . . . . . . . . . . . . . 435
Domain Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435
Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442
DNS Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444
Explore DNS Client Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449
Project 14-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451

Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452
15 Using NIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453
1. Overview of Network Information Services . . . . . . . . . . . . . . . . . . . . . . . 454
2. Discover NIS Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456
Databases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456
Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458
3. Setting Up a NIS Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
Project 15-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
4. Configure a NIS Client . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466
5. Setting Up a Secondary NIS Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469
16 SNMP System Management Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
1. Discover Elements of System Management . . . . . . . . . . . . . . . . . . . . . . . 472
System Heartbeat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
System Up/Down Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 473
xiv UNIX System Administration: A Beginner’s Guide
System Process Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474
Network Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474
System Configuration Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474
2. Explore the UCD SNMP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475
Common Command-Line Options . . . . . . . . . . . . . . . . . . . . . . . . . . 476
Environment Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482
3. Use the UCD Magement Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482
Snmpdelta Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482
Snmpget Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
Snmpgetnext Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 485
Snmpnetstat Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 486
Snmpset Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 491
Snmpstatus Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 496

Snmptable Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
Snmptest Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497
Snmptranslate Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 498
Snmptrap Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
Snmptrapd Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500
Snmpwalk Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 502
Snmpbulkwalk Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 505
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 507
17 Using Network File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 511
Versions of NFS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512
1. NFS Server Uncovered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513
The nfsd Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 513
The lockd Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 514
The statd Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515
The mountd Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515
2. Mounting Remote File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 515
The dfstab/export Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 516
Share/Export File Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517
3. Exploring NFS Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519
exportfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519
share/unShare (Solaris Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
showmount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521
nfsstat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 522
4. Configuring NFS Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526
5. Controlling the File System Mount Table . . . . . . . . . . . . . . . . . . . . . . . . . 528
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531
18 File Transfer Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533
1. Explore a Sample FTP Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535
Obtaining a Directory Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 537
Configuration Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539

Retrieving a File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 539
Sending a File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 540
Monitoring File Transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 541
2. Discover FTP Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 542
3. Controlling FTP Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543
4. Configure Anonymous FTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 546
Setting Up Anonymous Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548
5. Log FTP Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
Enable FTP logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
Enable the syslog Facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551
Project 18-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554
19 Important System Administration Tasks/Information . . . . . . . . . . . . . . . . . 555
1. Communicate with Users on the System . . . . . . . . . . . . . . . . . . . . . . . . . 556
2. Increase System Swap Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558
List Swap Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558
Add More Swap Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559
3. Control Root Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 560
4. Display System Configuration Information . . . . . . . . . . . . . . . . . . . . . . . 561
The /proc Directory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564
Project 19-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
20 Using DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
1. Use The Solaris DHCP Configuration Manager . . . . . . . . . . . . . . . . . . . . 574
Starting the Solaris DHCP Configuration Manager . . . . . . . . . . . . . . 574
Configuring DHCP Services for the First Time . . . . . . . . . . . . . . . . . 575
Using the Configuration Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . 583
Adding IP Addresses to the DHCP Server . . . . . . . . . . . . . . . . . . . . . 585
2. Configure DHCP Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593
Manual DHCP Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593

Set Up Automatic and Permanent DHCP Configuration . . . . . . . . . 594
Obtain DHCP Agent Status Information . . . . . . . . . . . . . . . . . . . . . . 595
Configuration of DHCP Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
Viewing Network Information on Windows . . . . . . . . . . . . . . . . . . . 598
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 604
21 Using rdist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 607
1. Create an rdist Distribution File for Synchronizing Files . . . . . . . . . . . . 609
2. Debug an rdist Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 611
3. Investigate rdist Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 612
Task Notifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 614
Excluding Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616
Invoking Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 617
Contents xv
4. Explore an rdist Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618
Project 21-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 620
Mastery Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 623
A Answers to Mastery Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 625
Module 1: Introduction to UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . 626
Module 2: Basic UNIX Commands . . . . . . . . . . . . . . . . . . . . . . . . . . 626
Module 3: Using System Administration Tools . . . . . . . . . . . . . . . . . 626
Module 4: Software Package Management Tools . . . . . . . . . . . . . . . 627
Module 5: Maintaining UNIX Users . . . . . . . . . . . . . . . . . . . . . . . . . 627
Module 6: File Systems, Disks, and Tools . . . . . . . . . . . . . . . . . . . . . 628
Module 7: System Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 628
Module 8: Backup and Restore . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Module 9: System Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Module 10: The TCP/IP Suite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629
Module 11: Basic Network Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . 630
Module 12: Advanced Network Tools . . . . . . . . . . . . . . . . . . . . . . . . 630
Module 13: Overview of SNMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631

Module 14: Using Domain Name System . . . . . . . . . . . . . . . . . . . . . 632
Module 15: Using NIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
Module 16: SNMP System Management Tools . . . . . . . . . . . . . . . . . 632
Module 17: Using Network File System . . . . . . . . . . . . . . . . . . . . . . 633
Module 18: File Transfer Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 633
Module 19: Important System Administration Tasks/Information . . 634
Module 20: Using DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 634
Module 21: Using rdist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 635
B Tools at a Glance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637
C Overview of MIB-II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 641
Discover MIB-II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 642
System Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643
Interfaces Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 647
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 657
xvi UNIX System Administration: A Beginner’s Guide
Acknowledgments
I
wish to thank my darling wife, Nita, known also as my better half, corporate
buddy, main squeeze, partner in crime, and overall the best companion I have
ever known. You truly are a gift from above! To JC for again talking and walking
with (and sometimes carrying) me when you were the only one that could help.
I also wish to thank the McGraw-Hill production staff for their
outstanding efforts in preparing the manuscript for production. Thanks go
to Lisa Wolters-Broder for handing the many details of chapter preparation
and to Emma Acker for coordinating the book process. Special thanks to
Franny Kelly, my acquistitions editor, for managing the Osborne UNIX series
and coordinating the fine art of book publishing. Thanks also to John Tiso for
reviewing the manuscript and providing critical feedback. Thanks to Jim Minatel
for adding important book elements to the chapters! Finally, special thanks to
Sam Yu for reviewing elements of the manuscript.

xvii
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Introduction
T
his book addresses the fundamentals of UNIX system administration and
focuses on the important elements of maintaining a small, medium, or large
network of UNIX systems. It tells you everything you need to know to be
a successful system administrator or manager. Even non-networked environments
are covered so that you are prepared to address the many different issues and
problems that are typically encountered with them.
Enterprise networks (or clusters) of UNIX systems have become the critical
link and key component of the information landscape for corporate America.
UNIX systems have been deployed within every corporate function and within
a broad section of businesses and markets. This widespread acceptance and
deployment means that UNIX systems are now more on the critical path than
ever before. In many corporations and institutions, a system failure or network
outage can have serious implications for the organization’s ability to conduct
standard business activities or communicate with their customers or key partners.
In the financial community as well as other market segments, even a relatively
small system failure or outage can result in significant financial impact or have
other far-reaching implications.
Many of today’s corporate and institutional UNIX sites are characterized
by significant growth in the diversity and the total number of systems installed.
In these heterogeneous computing environments, it is difficult to effectively
xix
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manage the many different computer systems and peripherals because much
of the system administration tasks are done in an ad-hoc manner, or lack
comprehensive tools. Sometimes tasks must even be done manually. A critical

system or network failure can significantly impact the use of corporate services
and affect the day-to-day operations of an organization. Many systems have
also been deployed with very little regard for their manageability or upgrade
capabilities. This makes the tasks of the system administrator that much harder
due to the added requirements of legacy systems, where key system tools are
not available with the basic system.
This book will give you the knowledge of important tools, step-by-step
procedures, and the skills necessary to effectively administer UNIX systems. It
is meant to be very practical in nature, and focuses on only the more important
elements to system administration, not esoteric subjects that have little relevance
to the important issues faced by today’s UNIX administrator.
Audience
The primary audience for this book is the beginning system administrator or
network manager, as the title suggests. If you already know the difference
between the netstat and mount commands, then this book might not be
up to your speed. On the other hand, if you have used some of these commands
before, but don’t really understand the bigger picture, or if you want additional
information about the commands or options, then this book will help guide
you. The book focuses more on how to use software tools and administration
procedures than on lengthy descriptions of operating system design or system
architecture. However, where appropriate, some theory of operation and/or
design is provided to ensure that you fully understand the mechanics of critical
services or functions.
UNIX Versions
All of the tools discussed in this book and the examples provided are from
Solaris and Linux, with some tools that are also based on the HP-UX operating
system. Because many of the UNIX tools are available across a wide variety of
versions of UNIX, you will have little difficulty adapting and using the tools in
other environments.
xx UNIX System Administration: A Beginner’s Guide

TEAMFLY

Team-Fly
®

Module1
Introduction
to UNIX

Critical Skills
1.1 Uncover the History of the UNIX System
1.2 Explore the Elements of a Computer System
1.3 Show the UNIX Timeline
1.4 Discover the Roles of the UNIX System Administrator
Copyright 2002 by The McGraw-Hill Companies, Inc. Click Here for Terms of Use.
B
efore you jump in and type your first UNIX command, you’ll benefit from
understanding some general background on how computer architecture is
organized. When you combine that knowledge with a brief history of UNIX and
what features UNIX provides, you’ll begin to understand some of the advantages
UNIX provides over other operating systems. From there, you are ready to learn
what a UNIX system administrator does, and you’ll see not all of those duties are
technical. So to start at the most basic level, you want to know what UNIX is.
1.1 Uncover the History
of the UNIX System
The UNIX system was introduced more than 30 years ago and is still one of the
most widely used and popular operating systems to this day. UNIX is used in
businesses, universities, institutions, and even individual homes to support a
variety of applications and functions. UNIX is quite universal and is used all
over the world by many different types of people for a host of different purposes.
UNIX is supported on a wide range of computer systems—from a single personal
computer to very large, high-end workstations and servers and even mainframe
class systems.
Certainly as expected, UNIX has gone through a myriad of changes and
modifications, which involved a large number of individuals, institutions,
and companies. UNIX has improved in many significant ways and as a result is
much more functional and provides a large pool of applications, tools, utilities,
and other software. The UNIX operating system has been ported to pretty much
every major computing platform and system architecture popular within

the computer industry. UNIX is available for just about all general-purpose
computer systems.
Typically, UNIX can be found on many common computer platforms and
users have direct interaction with the operating system. However, many turnkey
systems simply use UNIX to support one or more applications. The users of
these specialized systems generally interact with the application, but not UNIX
itself. It is very possible that many users of UNIX systems do not actually know
they are using UNIX, because their view of the system is restricted to the
application running on top of the operating system. UNIX has also found its
way and gained popularity in the embedded world, which means, like the
2 UNIX System Administration: A Beginner’s Guide
Module 1: Introduction to UNIX 3
1
turnkey approach, UNIX is hidden from the user community. The embedded
world contains a plethora of devices like cameras, controllers, handheld
devices, and just about anything else that supports a computer processor, and
UNIX can be used to provide a scalable, flexible system that can expand as the
device’s capabilities improve over time.
UNIX is constantly being improved, refined, and retooled. In other words,
it is still going through changes and enhancements. That is the beauty of
UNIX; like a fine wine, it gets better with age! As a system administrator, you
will be able to grow with UNIX—as it gets better, so will you as you become
more familiar with the system and specific tools. UNIX is many things to many
people. For the software writer, UNIX is a development platform to build
software. For general users of the system, it is using whatever applications they
need to accomplish their job. For the administrator, it is a system that changes
and must be maintained and improved over time. However, with these changes
comes challenges, and as a system administrator you will need to maintain your
knowledge of UNIX on a consistent basis in order to be effective.
1.2 Explore the Elements

of a Computer System
Every general-purpose computer system, no matter where it was designed or
manufactured, can be divided into functional areas or different modules so that
it can be explained and understood. Today, there is a large selection of computers
on the market. However, despite many different “brands” of systems, many
of them are based on a small number of common components and computer
architecture types. For example, in the personal computer space, the Intel
Pentium processor (and various clones) is one of the most popular throughout
the world. Despite this popularity, other computer systems such as the Apple
Macintosh and others continue to flourish. Generally speaking, every time a
dealer or maker sells a computer, it is shipped with both an operating system
and a set of applications. Without such software, the computer system would be
virtually useless because the user would have no way to interact with the system.
Figure 1-1 shows a diagram of the typical computer system, which contains
the different functional areas or modules within a computer. At the highest
level, applications are designed and written to accomplish very specific business
functions for users. At the lowest level, we have the physical hardware of the
computer. At this level all of the hardware-related services are available, such
as connecting to a network, saving information to secondary storage (that is,
hard disk drive), accessing the CPU, and so forth. Typically, these functions
are very specific to the type or architecture of the system as well as the different
kind of peripheral devices used. For instance, the way memory is allocated for
applications can be somewhat different for the different types of computers
available on the market today.
An operating system or OS can be generally described as software that
provides an interface layer for applications so that they can interact with the
hardware components of the computer. Some examples of popular operating
systems include the Macintosh OS, Windows 2000, Palm OS, and UNIX. Although
each of the operating systems mentioned are different in design and may contain
alternative user interfaces, they all provide most of the same basic features. At

the middle layer or operating system level, many of the hardware functions are
made available for the upper application level. For example, many computers today
come with a DVD or CD drive that can be used to view movies or play compact
discs (CDs) on the computer. The computer provides the ability to play music
though the internals of the system. However, in order to listen to your favorite
music CDs, the operating system must provide some user application that permit
access and control of the DVD or CD drive. The application must provide the
ability to play, stop, skip between tracks, eject the disc, and so forth when
necessary. Thus, the software application must control the hardware in order
for the user to experience the full use of the hardware. Additional examples of
operating system support for hardware include control and access to peripheral
devices such as printers, modems, networks, computer monitors, keyboard,
pointing devices, etc.
4 UNIX System Administration: A Beginner’s Guide
Figure 1-1
A diagram of the typical computer system